In general, a bill processing apparatus is incorporated into a service providing device, such as a game medium rental machine installed in a game hall, a vending machine or a ticket-vending machine installed in a public space, or the like, which identifies the validity of a bill inserted from a bill insertion slot by a user, and provides various types of products and services in accordance with a value of the bill having been judged as valid.
The above-mentioned bill processing apparatus is, as disclosed in Patent Document 1, for example, configured to determine what kind of bill the inserted one is (authenticity judgment). The bill processing apparatus disclosed in Patent Document 1 performs a bill authenticity judgment by utilizing length data, and a light emitting element and a light receiving element are installed in a traveling route through which the bill is carried, to detect a length of the inserted bill. In particular, pattern comparison means for comparing pattern data of the bill based on time-series output from the light receiving element with the reference pattern data corresponding to the kind of the bill is provided such that the authenticity of the bill is judged based on the detected length data and a comparison result by the pattern comparison means.
[Patent Reference 1] Japanese unexamined patent application publication No. H6-243234